I'm looking for a simple latch design. My project will have two roller chain sprockets positioned one above the other with about a two foot gap. A motor will turn one of the sprockets and the other is just an idler sprocket. A #40 roller chain will run around the two sprockets. Mounted just beside this chain and sprocket setup, will be a vertical slider rail with an object that travels up and down the rail. I need something attached to a chain link(s) that will circle the bottom sprocket, latch onto the object on the slider rail, drag/lift the object upwards, then release(drop) the object before, at, or while the chain link carries around the top sprocket. The latch mechanism must then again latch the object next time around the bottom sprocket and repeat the latch/lift/drop cycle indefinitely. I am looking for a simple design without incorporating additional motors or electronics if possible. I can add additional levers/pulleys or anything necessary. Please let me know. Thanks so much!